Page:UK Traffic Signs Manual - Chapter 8 - Part 1 (Traffic Safety Measures and Signs for Road). Designs 2009.pdf/155

DUAL CARRIAGEWAY ROADS there is any doubt, the structures should be replaced or strengthened prior to the works or, where appropriate, temporarily plating over may be considered.

The effects of existing and proposed carriageway drainage and hard shoulder runoff shall be taken into consideration.

Special care will be needed in respect of works near entry and exit slip roads, service areas etc. It may be necessary to close slip roads and service areas and arrange suitable diversions. Provision for these arrangements should be included in the works where appropriate.

Where the hard shoulder is to be utilised as a running lane and there is no refuge for any broken-down vehicle then a recovery vehicle service is recommended. The provision of a recovery service should depend on the length of road without hard shoulder or refuge and the implications of delay in removal of the broken-down vehicle on congestion and delay. The recovery vehicle service should be located on the approach to the affected length of hard shoulder so that the broken-down vehicle may be removed as quickly as possible to a suitable place of safety. These recovery vehicles should be available throughout the period of hard shoulder usage. The provision of a temporary CCTV system as an aid to the detection of broken-down vehicles and other incidents that could adversely affect traffic flow should be considered. See Sections D3.35 and D3.36.

Where the hard shoulder is used as a running lane, the provision of temporary verge refuges (suitably signed) should be considered to assist drivers of failing vehicles to pull off the highway beyond the running lanes. These should be provided every 500m and should be a minimum of 50m in length. As HGVs may needto use them the length and construction depth needs to be adequate for a loaded HGV.

The carriageway edge condition should be considered when running on the hard shoulder, see Section D3.19.

In order to comply with Motorway Regulations it will always be necessary to use a special sign to indicate to drivers that they may use the hard shoulder. This should be the "USE HARD SHOULDER" panel to diagram 7260 with a symbolic sign to diagram 7211.1, 7230, 7233 or 7234. The "REJOIN MAIN CARRIAGEWAY" panel to diagram 7261 with a symbolic sign to diagram 7231 or 7232 should be displayed in advance of the point where use of the hard shoulder should be discontinued. Traffic cones, warning lights and barriers will also be needed to indicate the path traffic should follow at the beginning of the obstruction. "Keep right" signs variant to diagram 610 must be used in conjunction with cones, warning lights and barriers at the end of the affected length to return traffic to the main carriageway, and to cancel the "USE HARD SHOULDER" message. Signs to diagram 7203.1, 7204 and variants, together with distance plates to diagram 7209, are to be used at 1/2 mile intervals to advise drivers of the status of the hard shoulder and adjacent lanes.

Works on dual carriageway roads may require some traffic lanes to be reduced in width to less than 3.0 m. Whenever this situation arises, advance warning of the narrow lanes should be given. In most situations it will be necessary to re-mark the carriageway showing the new lanes. Signs incorporating the "NARROW LANES" panel to diagram 7264 may also be used for cases where the lane reduction is less severe. If the lane width is less than 3.0m the symbol indicating a temporary width restriction, diagram 7283 or 7283.1, should be included for the appropriate lane or lanes.

Where the number of wider vehicles allows, narrower traffic lanes can be used to enable more lanes to be provided past the works area. The normal motorway lane width is 3.65 m. Where heavy vehicles including public service vehicles, caravans etc. are expected, the lane width may be reduced only to 3.25m (desirable minimum) and, where there is a shortage of space, an absolute minimum of 3.0 m. However, where the traffic is expected to consist only of cars and other light vehicles the lane width may be reduced to 2.75 m (desirable minimum) or 2.5m (absolute minimum). 154